Convalescent plasma therapy
– Is it treatment for COVID - 19?
The world seems to be vulnerable in
the face of the COVID – 19 pandemics, with over 4.1 million cases already and
over 282,000 deaths due to its infection. Scientists are working diligently to
develop the preventable vaccine and to prove the efficacy of many currently
available drugs including antivirals, protease inhibitors, nucleotide analog,
and interleukin inhibitors all around the globe. Convalescent plasma is another
therapeutic strategy that is under investigation to treat severe patients.
Convalescent plasma therapy uses
antibodies found in the blood of people who have recovered from infection (or
convalesced), to treat infected patients. In this, blood is drawn from a person
who has recovered from the disease, and the serum is separated and screened for
virus-neutralizing antibodies.
Back then in the late 1800s, the convalescent
blood product was used to treat infectious disease, firstly in treating
diphtheria. The therapeutic regimen was studied during the Spanish influenza
pandemic of 1918-1920. By the 1930s it was used widely to treat different
infectious diseases, such as scarlet fever and pneumococcal pneumonia. However,
with the development of antimicrobial, its use declined by the middle of the
20th century. Whenever new epidemics or pandemics emerges, the use of passive
antibody therapy has been renewed e.g., in previous corona virus outbreaks—SARS
in 2002–04 and Middle East respiratory syndrome in 2012. For other infectious
diseases, the positive results guided WHO to publish guidance on the use of the
treatment for Ebola virus disease, and treatment benefits have shown lower
mortality in patients with severe pandemic influenza A(H1N1) 2009 virus (H1N1
2009). However, definitive clinical evidence showing the efficacy of
convalescent plasma is scarce.
Recently, two small studies were
done in China, a case series of five critical patients receiving mechanical
ventilation and a pilot study done in ten severe COVID-19 patients. The
convalescent plasma therapy showed to be safe and improvement in clinical
outcome, including fever, Sequential Organ Failure Assessment score, and
respiratory symptoms, in some cases within 1–3 days of treatment. The US Food
and Drug Administration has approved the use of this therapy under
compassionate use rules. Other trials are also planned or underway in China,
Colombia, Iran, Mexico, and the Netherlands. However, it's not easy to find
enough people who are eligible to donate. It is expensive and cannot be done on
a large scale.
The success of convalescent plasma
therapy depends on the donation of plasma by the people who have recovered from
COVID-19 and have high concentrations of anti-SARS-CoV-2 antibodies. Survivors
will be able to donate only twice, 400 ml each time, possibly saving 2-3 lives.
The donor and the patient must be of compatible blood types, and the plasma is
then tested for multiple diseases, including COVID-19, Hepatitis, and HIV.
Then, again tested to make sure it has enough antibodies to effectively treat
or prevent COVID-19. This type of immunity provides immediate protection
against the antigen but is not long-lasting.
In Nepal, the Ministry of Health and
Population is also planning to use the plasma therapy and has directed a team
of experts to prepare the directives to support plasma therapy for the
treatment of corona virus-infected patients.
The main challenges for the health
care provider might be finding eligible donors and implementing testing to
confirm adequate antibody levels in plasma. Likewise, blood transfusion
reactions, another potential complication is the transmission of unknown
pathogens and infection risk to laboratory personnel processing the plasma.
References
Chen, L., Xiong, J., Bao, L., & Shi, Y. (2020).
Convalescent plasma as a potential therapy for COVID-19. The Lancet.
Editorial. (2020, May 01). The resurgence of
convalescent plasma therapy. The Lancet Haematology.
Kai Duan, B. L. (2020). Effectiveness of convalescent
plasma therapy in sever COVID-19 patients. Proceedings of the National
Academy of Science of the United States of America. USA.
Marano, G., Vaglio, S., Pupella, S., Facco, G.,
Catalano, L., Liumbruno, G., & Grazzini, G. (2016). Convalescent plasma:
new evidence for an old therapeutic tool? Blood Transfusion.
Shah, D. R. (2020, April 09). Plasma therapy: New
hope for COVID 19. The Himalayan Times.
https://swasthyakhabar.com/story/32351
